Where do you draw the line?

I agree that stem cells offer limitless potential in the understanding of cell biology but I do find the thought of mixing human stem cells with animal cells a little disturbing. As it stands, the law fails to keep in step with technological advances. If scientists start experimenting with stem cells to create human brain tissue in other animals an ethics catastrophe will ensue. Our system of anthropocentric allocation of rights flies out the window. Do humans deserve more protection than a monkey with a human brain? After all isn't it the brain that distinguishes us from other animals? Scientists with little interest in animal welfare will no doubt exploit these new creations. These scientists will find an unexpected ally in the evangelicals. Believing it is the soul and not the brain that indicates a human these people will find it easier to accept this type of science. They probably take more issue with the concept of cloning. Something I am less opposed to.